1. Field
Some example embodiments relate to methods and apparatuses for a photodetector using bandgap-engineered 2-dimensional (2D) materials and a method of manufacturing the same, and more particularly, to a photodetector using bandgap-engineered 2D materials and a method of manufacturing the same.
2. Description of the Related Art
A photodetector has been widely used as a light-receiving device in an optical communication network, a precise measuring system, etc. A recent communication network aims at a 4th generation communication network that may operate at terahertz (THz) to process massive data, including a moving image, at a relatively high speed. Therefore, respective parts that are put into a communication network have been reengineered in structures appropriate for processing relatively high-speed massive data.
A graphene is known for effective masses of electrons and holes approximate to 0 at a Dirac point. Therefore, carriers may be theoretically moved at a speed of 1/300 of light in the graphene, and thus the graphene is known as having a higher mobility than existing known materials. Also, an energy bandgap of the graphene is 0 eV at the Dirac point. Therefore, the graphene may absorb light in most wavelength bands and thus enables a broadband transmission. As a result, massive data may also be transmitted at a relatively high speed by using the graphene. Also, the graphene includes a first layer having a sheet resistance of about 100 ohm/sq and has a light absorption rate of about 2.3%. Therefore, the graphene may be used as a transparent electrode and may be used in a photodetector.
In general, a photodetector using a Transition-Metal Dichalcogenide (TMD) having a relatively high photoelectric sensitivity has been mainly used for photodetection. Because a TMD material has a light absorption rate about 100 times higher than silicon, a photodetector that is thin, but also highly efficient, may be manufactured.
In a photodetector using a graphene and a TMD described above, a TMD material absorbs light, and thus generated electrons and holes can travel to graphene electrodes on both sides. Here, if the TMD material absorbing light directly contacts the graphene electrodes and is not exposed to light, a dark current may flow according to an applied voltage.